Boiler



Dec. 27, 1938.; H. E. KLEFFl-:L

BOILER s sheets-sheetL 1 Filed May 5, 1936 ATTORNEYS Dec. 27, 1938. H.E. KLEFFEL 2,141,917

BOILER Filed May 5, 1936 3 Sheets-Sheet 2 Dec. 27, 1938. H. E.-KL.EFFEL2,141,917

BOILER a Filed May 5, 195e s sheets-sheet 3 Q I Egli:

ATTORNEYS Patented Dec. 27, 1938 UNITED STATES PATENT OFFICE 4 Claims.

This invention relates to steam boilers and furnaces therefor and isconcerned more particularly with improved boilers of the horizontalreturn tubular and similar types containing various novel features ofconstruction, the use of which improves the combustion efficiency in theburning of the fuel in the furnace and adds to the steam productioncapacity of the boiler. The boilers of the invention are based on theprinciples disclosed in my Patents Nos. 1,884,741 and 1,884,742,1andmay, therefore, be considered to constitute improvements on the patentedapparatus. The new boilers depart from the disclosures of the patents invarious respects, however, and these features will be pointed outhereafter in detail.

As explained in the patents referred to, efficient combustion in aboiler furnace requires that the gases be consumed to as great an extentas possible before they reach the bare heat absorption surface in theboiler. `As a result, it was the common practice prior to my patentedinventions to construct large furnace chambers through which the burninggases would flow unobstructed in a streamline manner without appreciablemixing and turbulence, thus requiring a long path of travel so that thefuel could be substantially completely burned before leaving thechamber. Such large combustion chambers were frequently lined with waterWalls, and because of that and of their size, their cost of installationwas high. The inventions of the patents are directed to the provision offurnace chambers in which substantially complete combustion can beattained without the chambers being of such large dimensions as werepreviously considered necessary, and in the patented apparatus, thedesired combustion efficiency is achieved by providing means in theregion in the chamber in which combustion is taking place for creatingturbulence in the gas stream and thereby promoting diffusion of thegases with the air.

In the patented apparatus, the desired turbulence and mixing of thegases and air is obtained by the use of a bank of water tubes in thefurnace chambers in the path of the owing gases in a zone of relativelyhigh temperature, the tubes in the bank being so arranged as to providea plurality of passages through which the gases flow on their way out ofthe chamber. Such water tubes, if wholly bare, however, will extract somuch heat from the burning gases as to reduce the temperature of thegases which come in contact with the tubes below the combustiontemperature and will, therefore, hinder rather than promote combustion.Accordingly, the tubes are covered, wholly or in part, by a coveringwhich permits the contents of the tubes to absorb heat only at a limitedor controlled rate, so that the gases are not cooled to a detrimentalextent. 5 Since the tubes are connected in the water circulation of theboiler, they add to its steam production capacity and at the same timethe Water in the tubes serves to protect the covering, so that thecovering has a long life.

The present invention involves the application of the principles of thepatented inventions to boilers of the horizontal return tubular andsimilar types, and in such a boiler, Water tubes connected in the watercirculation of the boiler are installed in the furnace chamber in a bankor plurality of rows lying a substantial distance below the boilershell. These tubes extend through the furnace chamber from end to endand they lie inclined to the horizontal and generally transverse to thedirection of flow of the gas stream. In that portion of the furnacechamber in which combustion is taking place, the tubes are covered by acovering which controls the rate of heat absorption, and elsewhere,particularly in the region where the combustibles in the gases have beensubstantially fully consumed, the tubes are bare. If desired, the bankof tubes mayv be made up of a plurality of units each consisting of apair of horizontal headers and a row of tubes connecting the headers,with the tubes in adjacent headers either aligned in vertical rows orstaggered, In a modified construction, the tubes of the bank areconnected to vertical headers and in that part of the furnace chamberwhere combustion is initiated, the tubes lie along the sides of thechamber and are covered, while in the remainder of the chamber, thetubes lie somewhat more directly in the path of the burning gases andare in part covered and in part bare, the covering lying in the regionwhere combustion is continuing. With either construction, the tubes inthe furnace chamber tend to prevent stratification in the gas stream andcreate turbulent conditions which accelerate the rate of combustion. Atthe same time, the tubes add substantially to the steam productioncapacity of the boiler.

As another feature, the invention includes a novel covered tube whichmay be used in the bank of tubes in the furnace chamber for the purposesabove described. This new tube includes a refractory or heat insulatingcovering and a simple and effective means by which the covering may bemaintained in place on the outside of the tube.

For a better understanding of the invention, reference may be had to theaccompanying drawings in which Figure 1 is a longitudinal section of ahorizontal return tubular boiler with a bank of tubes of the inventiondisposed in the furnace chamber below the boiler shell;

Figure 2 is a view of the boiler shown in Figure 1, partly in frontelevation and partly in section on the line 2 2 of Figure 1;

Figure 3 is a sectional view on the line 3--3 of Figure 1;

Figure 4 is a developed view of a sleeve employed in retaining thecovering on the tubes of the bank;

Figure 5 is a cross-sectional view of a covered tube with a sleeve inplace;

Figure 6 is a view similar to Figure 4 showing a modified construction;

Figure '7 is a-longitudinal section of a modified form of the tube bankof the invention; and

Figures 8 and 9 are sectional views on the lines 8 8 and 9-9,respectively, of Figure 7.

Referring now to the drawings, the boiler illustrated in Figure 1includes a shell I0 containing fire tubes II and supplied with feedwater through a pipe I2 and having a steam discharge pipe I3 and ablow-off discharge pipe I4 of the usual construction. The shell ismounted on a setting consisting of front and rear walls I5, IB and sidewalls I'I, these walls defining a furnace chamber I8 and a passage I9through which the gases pass from the chamber to the re tubes I I.

Fuel in any desired form, solid, liquid, or gaseous, may be supplied tothe furnace chamber for combustion therein, and in the constructionillustrated, the furnace is of the hand fired type and includes a grate28, carrying a bed of fuel 2| which is replenished through the door 22.Within the furnace chamber to the rear of the grate is the usual bridgewall 23 provided with a stub baille 24 at its top, and rearward of thebridge wall is the baffle 25, the baffles being so arranged that thegases flow in a generally upward direction from the fuel bed over thetop of the bridge wall and stub baiile, then downward beneath the lowerend of the baffle 25, and then upward in the passage I9 to the firetubes. After flowing through the re tubes, the gases pass through theexit flue 26 and are discharged. Particles of ash carried along by thegases are collected in the fiy ash pocket 21 beyond the bridge wall andmay be removed through the rear door 28.

Within the furnace chamber below the boiler shell is a bank of tubesgenerally designated 29, these tubes extending lengthwise of the furnacechamber and througha portion of the passage I9, and lying substantiallytransverse to the direction of flow of the gases in their successivepasses in the furnace chamber and passage. The tubes are connected attheir ends to horizontal headers 30 and 3l, the headers 30 beingsupplied with water from the boiler shell through downcomers 32connected to the headers by nozzles 33. The uptake headers 3| dischargesteam and water through nozzles 34 into riser pipes 35 which eX- tendupwardly along the sides of the boiler shell and discharge into it atpoints 36 which lie at or above the water line. The tubes in the bank 29are thus connected to the boiler shell in such a manner that a positivecirculation through the tube bank is provided countercurrent to the flowof burning gases, and improved water circulation within the boiler shellis obtained.

As shown in Figures 2 and 3, the units of the bank, each consisting of apair of headers 30, 3| and tubes 3'I between the headers, may be ofkinds which differ with respect to the arrangement of the tubes relativeto the headers and by the proper selection of units in constructing thebank, gas passages through the bank of different forms may be provided.With any arrangement, the wide spacing and location of the tubes in thepath of the traveling gases causes the tubes to create turbulence in thegas stream so that the burning gases are thoroughly mixed with the airnecessary to insure 'complete combustion.

In that part of the furnace chamber directly above the grate, that is,in the region where combustion is initiated, the tubes, if bare wouldabsorb so much heat from the gases contacting with them as to lower thetemperature of those gases below that of combustion, and would thushinder rather than promote combustion. Accordingly, in this portion ofthe furnace chamber, as well as in the first pass between the baiiies 24and 25, where combustion is continuing, the tubes are provided withcoverings which limit and control the amount of heat absorbed by thecontents of the tubes. Beyond the baille 25, the gases are substantiallycompletely consumed and the portions of the tubes in the last pass ofthe gases upward through the passage I9 are bare so that these parts ofthe tubes may act as more effective heat absorbing surface.

In the construction shown in Figures 7 to 9, inclusive, the boiler shell38 with re tubes 39, feed water pipe 4G, steam discharge pipe 4I, andblow-off discharge 42 is of the construction previously described. Theboiler setting again includes front and rear walls 43, 44, and sidewalls 45, 46 defining a furnace chamber 41 with a passage 48 leadingfrom the chamber to the fire tubes, and within the furnace chamber is abridge wall 49 and a baille 50. The furnace chamber illustrated is ofthe mechanically fired type with the fuel supplied by means of a burner5I which may be supplied with powdered fuel, oil, gas, or a combinationof such fuels.

Outside the rear wall 44 of the setting is a vertical header 52 fromwhich lead tubes 53 arranged in a bank and Within the passage 48 and inthe pass in the furnace chamber between the bridge wall 49 and baille50, the tubes lie spaced across the furnace chamber and passage. At theforward end of the pass, the tubes are bent outwardly, and forward ofthe bridge wall 49, the tubes lie along the side walls of the combustionchamber. Beyond the front Wall 43, the two groups of tubes are connectedto vertical headers 54 from which lead risers 55 which discharge intothe boiler shell at or above the water line at the points 56. Water fromthe shell is supplied to the rear header 52 through downcomers 5l.

With the construction shown in Figure 7, those portions of the tubes 53which lie within the furnace chamber ahead of the bridge wall and in thepass between the bridge wall and the baffle 570 are provided with acovering so that the tubes may create the desired turbulence in thegaseous stream, without abstracting so much heat from the gases as tointerfere with their combustion. Beyond the baffle 58, the tubes 53 arebare so that they may absorb the maximum, abount of heat from the gases,the combustion of which has been completed.

Various types of coverings for the tubes may be provided and in Figures4 to 6, inclusive, I have shown two different forms of such tubes. Inthe construction shown in Figure 5, the tube proper 58 is inclosedwithin a metal shell made up of arcuate metallic sleeves 59 providedwith edge flanges 6D which are secured together by welding. The tubesshown in Figure 5 are provided with two sleeve sections which are ofsemicylindrical shape, but more such sections may be used if desired.Each section is formed of a fiat sheet of metal which is then bent tofit the outside of the tube and it is provided with a plurality ofprojections Eil formed by punching and piercing the sheet at spacedpoints and forcing the metal out of the plane of the sheet so as to formthe rough projections indicated. After formation of the projections,they are preferably bent over or rosetted. The necessary number of suchsections are then applied so as to t the tube tightly, and the sectionsare secured in place by having their flanges welded together. The heatinsulating or refractory material 62 is next applied in plastic form onthe outside of the sleeve, this material being held in place by theprojections which interlock with the covering and hold it securely inplace after the covering has set. In the construction shown in Figure 6,the sheet of metal 63 which is to form a sleeve section is pierced so asto provide tongues 54 of generally triangular shape. These tongues arethen bent over and provide a means for holding and interlocking therefractory covering in place on the tube.

Sleeves ofcthe construction described not only serve as a simple andeffective means for securing the refractory covering on the tubes, butthey also strengthen the tubes against bursting and bending. The sleevesare of relatively light weight and low cost, and can be easily fitted tothe tubes either in the shop or in the field. While the sleeve sectionsmay be best secured together by welding, other methods such as rivetingor clamping may be employed for the purpose. Similarly, the projectionsformed from the sleeves may be made in other ways and with otherA shapesthan those above referred to. The character of the covering employed ona particular tube depends on the use of the tube, and the kind ofcovering material and the thickness of the covering may be variedaccording to particular conditions of use.

In all adaptations of the invention, the tubes are so distributed in thefurnace chamber as to produce the desired eect of acceleratingcombustion, and the extent to which the tubes are covered will be variedso that the desired combustion conditions are obtained. The bareportions of the tubes provide heat absorptive surface of a highlyeffective type and by properly proportioning the covered and baresurfaces of the tubes, increased combustion efficiency and increasedsteam production capacity are obtained.

I claim:

l. In a boiler installation,.the combination of a furnace chamber havinga zone in which combustion of fuel takes place, means for introducingfuel into the furnace chamber for ignition and combustion therein, afire tube boiler, the inlet to the tubes of which is beyond the furnacechamber in the direction of flow of the gases of combustion, a zonebetween the inlet to the fire tubes of said boiler and the zone in whichcombustion of the fuel takes place through which the gases of combustionflow after combustion of fuel is substantially completed, a bank ofWater tubes extending through said zones and connected with said boilerto provide a circulatory system, at least a portion of those tubes ofsaid bank which pass through the zone in which combustion of the fueltakes place being covered with refractory material, and at least aportion of the tubes which pass through the zone in which combustion ofthe fuel is substantially completed being bare, the tubes of said bankbeing spaced from'one another to provide passage for the fuel beingconsumed and the gases of combustion, the tubes of said bank extendinggenerally transverse to the direction of ow of the gases, whereby thepassage of gases between and about said tubes causes diffusion andturbulence thereof.

2. In a boiler installation, the combination of a furnace chamber havinga zone in which combustion of fuel takes place, meansfor introducingfuel into the furnace chamber for ignition and combustion therein, afir-e tube boiler, the inlet to the tubes of which is beyond the furnacechamber in the direction of flow of the gases of combustion, a Zonebetween the inlet to the re tubes of said boiler and the zone in whichcombustion of the fuel takes place through which the gases of combustionflow after combustion of fuel is substantially completed, a bank ofwater tubes extending through said zones and connected with said boilerto provide a circulatory system, bale means for causing the fuel beingconsumed and the gases of combustion passing between and about saidtubes to take a tortuous course, at least a portion of those tubes ofsaid bank which pass through the zone in which combustion of the fueltakes place being cover-ed with refractory material, and at least aportion of the tubes which pass through the zone in which combustion ofthe fuel is substantially completed being bare, the tubes of said bankbeing spaced from one another to provide passage for the fuel beingconsumed and the gases of combustion, the tubes of said bank extendinggenerally transverse to the direction of flow of the gases, whereby thepassage of gases between and about said tubes causes diffusion andturbulence thereof.

3. In a boiler installation, the combination of a furnace chamber havinga zone in which combustion of fuel takes place, means for introducingfuel into the furnace chamber for ignition and combustion therein, a retube boiler, the inlet to the tubes of which is beyond the furnacechamber in the direction of flow of the gases of combustion and in partlocated over the furnace chamber, a zone between the inlet to the firetubes of said boiler and the zone in which combustion of the fuel takesplace through which the gases of combustion flow after combustion of thefuel is substantially completed, water tubes extending through saidzones and connected with said boiler to provide a circulatory system, abridge wall in said combustion chamber, a baille beyond the bridgeWallin the direction of flow of the gases of combustion, said watertubes lying in two groups extending along the sid-e walls of thecombustion chamber forwardly of the bridge Wall and forming a bank inthe combustion chamber to the rear of the bridge wall, at least aportion of the water tubes which pass through the zone in whichcombustion of the fuel takes place being covered with refractorymaterial, and at least a portion of the tubes which pass through thezone in which combustion of the fuel is substantially completed beingbare, vsaid water tubes being spaced from one another to providepassages for the fuel being consumed and the gases of combustion, saidtubes extending generally transverse to the direction of flow of thegases, whereby the passage of gases between and about said tubes causesdiffusion and turbulence there- 4. In a boiler installation, thecombination of a furnace having a zone in which combustion of fuel takesplace, means for introducing fuel into the furnace chamber for ignitionand combustion therein, a re tube boiler, the inlet to the tubes ofwhich is beyond the furnace chamber in the direction of flow of gases ofcombustion, a zone between the inlet to the re tubes of said boiler andthe zone in Which combustion of the fuel takes place through which thegases of combustion flow after combustion of the fuel is substantiallycompleted, a bank of water tubes extending through said Zones, at leasta portion 'of those tubes of said bank which pass through the zone inwhich combustion of the fuel takes place being covered with refractorymaterial, and at least a portion of the tubes which pass through thezone in which combustion of the fuel is substantially completed beingbare, said bank of tubes being connected to said boiler to provide acirculatory system such that the water ows through said tubes from thebare portions to the covered portions and in a direction countei'currentto the direction of oW of the gases, the tubes of said bank being spacedfrom one another to provide passages for the fuel being consumed and thegases of combustion, the tubes of said bank extending generallytransverse to the direction of flow of the gases, whereby the passage ofgases between and about said tubes causes diffusion and turbulencethereof.

HARRISON E. KLEFFEL.

